The present invention relates to laser diode optics and more specifically to coupling the emission from a laser diode to small lenses, also know as microlenses.
Because of the large numerical aperture of laser diodes it is necessary to use lenses of a short focal length and therefore a small physical size. The use of such lenses poses special problems in keeping the lens accurately placed relative to the emission point of the laser diode. It is common to require alignment of better than one micron between the optical center of the lens and emission point of the diode. The problem is compounded on wide diodes, such as wide area emitters or multi-element laser diodes. The emission area of these diodes is elongated and sometimes deviates from a straight line due to distortion caused by mounting the diode on the heatsink. When the diode is bent the alignment problem is aggravated since the lens has to be bent to match the curvature of the diode in order to avoid magnifying the curvature due to the effect of the short focal length.